Definitions

Airports:
Total number of airports. Runways must be useable, but may be unpaved. May not have facilities for refuelling, maintenance, or air traffic control.

Airports > Per capita:
Total number of airports. Runways must be useable, but may be unpaved. May not have facilities for refuelling, maintenance, or air traffic control. Per capita figures expressed per 1 million population.

Commute > Distance:
Distance. Based on 0-50 contributions for Argentina, Armenia, Austria and 63 more countries and 50-100 contributions for Australia, Brazil, Germany and 5 more countries and over 100 contributions for Canada, India, and United States. The surveys were conducted by numbeo.com from January, 2011 to February, 2014. See this sample survey for the United States, respondents were asked "Distance".

Motor vehicles > Per 1,000 people:
Motor vehicles include cars, buses, and freight vehicles but do not include two-wheelers. Population refers to midyear population in the year for which data are available."

Passenger cars > Per 1,000 people:
Passenger cars refer to road motor vehicles, other than two-wheelers, intended for the carriage of passengers and designed to seat no more than nine people (including the driver)."

Rail lines > Total route-km:
Rail lines are the length of railway route available for train service, irrespective of the number of parallel tracks."

Road density > Km of road per 100 sq. km of land area:
Road density is the ratio of the length of the country's total road network to the country's land area. The road network includes all roads in the country: motorways, highways, main or national roads, secondary or regional roads, and other urban and rural roads."

Roads > Passenger cars > Per 1,000 people:
Passenger cars (per 1,000 people). Passenger cars refer to road motor vehicles, other than two-wheelers, intended for the carriage of passengers and designed to seat no more than nine people (including the driver).

Roadways > Unpaved:
This entry gives the total length of the road network and includes the length of the paved and unpaved portions.

Vehicles > Per km of road:
Vehicles per kilometer of road include cars, buses, and freight vehicles but do not include two-wheelers. Roads refer to motorways, highways, main or national roads, secondary or regional roads, and other roads. A motorway is a road specially designed and built for motor traffic that separates the traffic flowing in opposite directions."

Waterways:
The total length and individual names of navigable rivers, canals, and other inland bodies of water.